Panoramic Radiography Flashcards
in panoramic radiographs, the sensor swings _____
in front of the patient
in panoramic radiographs, the x-ray source swings _____
behind the patient
_______ are unique to panoramics
ghost artifacts
for anterior teeth, the source must first go through the _____
spine
for the Lt/Rt areas, the source must first go through the ____
opposite side (To get a right side image, source must travel first through the left)
having the x-ray beam travel through Lt mandible to Rt mandible to sensor OR spine to anterior to sensor creates….
ghost artifacts
ghost artifacts usually have the same _____ as the image that formed it
right-left orientation
ghost artifacts are usually seen _____ than the object that forms the ghost
higher up on the radiographic image
examples of ghost artifacts
- mandibular ramus
- screws
- earrings
- Pt positioned too far back
- spine
common features of ghost artifacts (4)
- same general shape
- appear on opposite side of image
- positioned higher
- more blurred than real image
the farther an object from the x-ray source/closer to the source, the more ____ and ______
magnified and more blurry
the close an object to the x-ray sensory/the farther from the source, the more ____
minified
minimized images/magnification can be used to identify _____
position errors
anteriorly positioned
- anterior teeth horizontally minimized
- excess spine at sides of image
posteriorly positioned
- anterior teeth horizontally magnified
- loss of TMJs off sides of image
chin tipped down positioned
- excess arch smile
- excess distortion
- loss of TMJ off the top of image
chin tipped up
- flat/inverted smile
- excess distortion
- superimposes palate on Mx teeth
- Can see loss of TMJ image
rotation error/lateral displacement of midline
- teeth/ramus closer to the x-ray source are horizontally maginified
- teeth/ramus farther from source are horizontally minimized
slumped spine artifact
creates broad opaque mandible
bilateral oral airway artifacts
- impairs visualization of Mx apices
- tongue must stay up
most common panoramic image error
oral airway artifact (where the patient doesn’t keep tongue up)
swallowing artifact
- hyoid bone
- airway space
movement vertically during exposure creates…
vertical movement (“band”) artifact
movement horizontally results in…
duplication of structures or deletion of structures
remove ____ for panoramic
- earrings/piercings
- glasses
- RPD
- dentures
CBCT acquisition geometry
- source/receptor rotate around patient
- series of 2D projection images
- computerized reconstruction of 3D info
another word for 3D information/pixels
voxels
CBCT is dimensionally ____, relatively _______ imaging of hard tissues
accurate, high resolution
CBCT has good imaging of soft tissues/air interfaces, but poor ______
soft tissue differentiation (muscle vs fat vs fluid)
CBCT has (more/less) information than a panoramic
more
three ways to view CBCT
- slicing
- volume rendering
- reconstructed radiographs
CBCT scans: slices/section details
- most accurate
- most detailed
- when lost, use crosshairs
- dimensionally accurate
most common view, standard anatomic planes axial/sagittal/coronal
multiplanar reformatted (MPR)
convention for CBCT is viewing “____”
toes up
CBCT scans: volume rendering details
- spatial relationship
- dimensionally accurate
- threshold settings significantly influence appearance of tissue
- NOT reliable to assess fine details or bone quality
CBCT scans: reconstructed radiograph details
- not reliable for fine bone details
- great for quick overviews
- great for cephalometric analysis
- no spine image
- not dimensionally accurate
do reconstructed panoramics have ghost artifacts?
no, they do not
artifacts in CBCT
- patient motion
- metal streak
any distortion or corruption of image information that misrepresents reality
image artifact
patient motion artifacts (CBCT)
- double contours
- excessive double streaking
how to limit patient motion artifacts
- patient education
- straps
- faster scan times
CBCT artifact resulting from patient motion
patient motion artifact
CBCT artifact resulting from x-ray’s inability to penetrate metal/other dense material
metal streak artifact
metal streak artifacts (CBCT)
- combination of light/dark streaking artifacts surrounding dense objects
- usually confined to axial planes
how to limit metal streak artifacts
remove what metal you can
3 types of field of view
small, medium, large
small FOV gets…
teeth (dental)
medium FOV gets..
dentoalveolar
large FOV gets…
maxillofacial
voxels range
0.5mm to less than 0.1mm
the smaller the FOV, the ____ the allowed voxel size
smaller
